Process for the production of methacrolein and methacrylic acid

ABSTRACT

The present invention provides a process for the production of methacrolein and methacrylic acid by the gas phase catalytic oxidation of isobutylene or t-butanol at high temperature using molecular oxygen in the presence of catalyst consisting of molybdenum, tungsten, bismuth, iron, nickel, antimony, and an alkali metal, to which zinc or lead is added, and further phosphorus sulfur, silicon, selenium, germanium or boron, and magnesium, cobalt, manganese or tin are added.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a process for the production of methacroleinand methacrylic acid by the gas phase catalytic oxidation of isobutyleneor t-butanol using molecular oxygen, and more specifically to certainnew catalysts used in the process thereof.

2. Description of the Prior Art

Numerous catalysts have been proposed for use in the production ofmethacrolein and methacrylic acid via the catalytic oxidation ofisobutylene or t-butanol in a gas phase at high temperatures. Forexample, U.S. Pat. Nos. 4,380,664 and 4,111,984 disclose the use ofMoSbBiFeNi(Sn)[K, Rb, Cs][Co, U, Ge, W, Ti] catalysts in the gas phasecatalytic oxidation of isobutylene and t-butanol, respectively.Similarly, Japanese Patent Publication [Kokai] No. 27709/77 disclosesthe use of MoSbBiFeCo[alkali metals][Ni, Sn, Cr, Mn, Ti, W, Mg]catalysts in the gas phase catalytic oxidation of isobutylene. However,from an industrial standpoint, improvement still needs to be made in theperformance of the catalysts used in this reaction, especially withregard to such properties as catalytic activity, selectivity formethacrolein and methacrylic acid, and life of the catalyst.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, there is provided a process for theproduction of methacrolein and methacrylic acid comprising the gas phasecatalytic oxidation of isobutylene or t-butanol using molecular oxygenin the presence of a catalyst having the formula

    Mo.sub.a W.sub.b Bi.sub.c Fe.sub.d Ni.sub.e Sb.sub.f X.sub.g Y.sub.h Z.sub.i A.sub.j O.sub.k

wherein Mo, W, Bi, Fe, Ni, Sb, and O are respectively molybdenum,tungsten, bismuth, iron, nickel, antimony, and oxygen; X is at least oneelement selected from the group consisting of potassium, rubidium, andcesium; Y is at least one element selected from the group consisting ofphosphorus, boron, sulfur, silicon, selenium, and germanium; Z is atleast one element selected from the group consisting of zinc and lead; Ais at least one element selected from the group consisting of magnesium,cobalt, manganese and tin; and a, b, c, d, e, f, g, h, i, j, and krepresent the atomic ratios of the respective elements, such that whena=12, b=0.001-2 and preferably 0.01-2, c=0.01-3 and preferably 0.1-2,d=0.01-8 and preferably 0.1-5, e=0.01-10 and preferably 0.1-10, f=0.01-5and preferably 0.1-3, g=0.01-2 and preferably 0.1-2, h=0-5 andpreferably 0.001-2, i=0.01-5 and preferably 0.1-5, j=0-10 and preferably1-10, and k is the number of oxygen atoms sufficient to satisfy thevalences of the above components.

The molybdenum, tungsten, and antimony starting materials used in thepreparation of catalyst employed in this invention should preferably beoxides or compounds that yield oxides under intense heating.

Examples of such compounds include ammonium molybdate, ammoniumparatungstate, antimony trioxide, and the like. The starting materialsfor the other elements should preferably be oxides, chlorides, sulfates,nitrates, carbonates, or mixtures thereof. Known methods such asevaporation to dryness, precipitation, and oxide mixture may be employedin the preparation of the catalyst. The use of a carrier is desirable.Silica, alumina, silica/alumina, and the like may be used as thecarrier.

In working the invention, molecular oxygen is added to isobutylene ort-butanol as the starting material, and gas phase catalytic oxidationcarried out in the presence of the above-described catalyst. The molarratio of isobutylene or t-butanol to oxygen should lie within the rangeof 1:0.5 to 1:3. The feedstock gas should be diluted with an inert gasfor use. The molecular oxygen used for oxidation may be pure oxygen gasor air, although air is more advantageous for industrial applications.The reaction pressure may range from normal pressure to severalatmospheres. A temperature lying within the range of 250° to 450° C. ispreferable. The reaction may be conducted either on a fluid or fixedbed.

The present invention makes possible the industrially advantageousproduction of methacrolein and methacrylic acid from isobutylene ort-butanol, in addition to which it has the effect of providing a longcatalyst life.

EXAMPLES

All references to "parts" in the examples below signify parts by weight.Analyses were carried out by gas chromatography. The conversion (%) ofisobutylene or t-butanol, the selectivities (%) for methacrolein andmethacrylic acid, and the combined single-pass yield (%) of(methacrolein and methacrylic acid) are defined below: ##EQU1##

EXAMPLE 1

Ammonium molybdate (500 parts), 18.5 g of ammonium paratungstate, and27.8 g of rubidium nitrate were added to 1000 parts of water, and themixture heated under stirring, giving solution A.

In a separate step, 250 parts of 60% nitric acid was added to 850 partsof water, then 114.5 parts of bismuth nitrate added and dissolved inthis. This was followed by the successive addition and dissolution of286.0 parts ferric nitrate, 480.4 parts nickel nitrate, 90.8 partsmagnesium nitrate, and 35.1 parts zinc nitrate, giving solution B.

After adding solution B to solution A, 51.6 parts of antimony trioxidewas added to the resulting slurry, the mixture heated under stirring,and most of the water evaporated off. The cake-like substance obtainedwas dried at 120° C. and molded by calcining for ten hours at 500° C.The composition of the catalyst thus obtained was Mo₁₂ W₀.3 Bi₁ Fe₃ Ni₇Mg₁.5 Zn₀.5 Sb₁.5 Rb₀.8 O_(X). Since the atomic ratio X for oxygen isdetermined naturally by the valences of the other elements, this isomitted hereafter.

This catalyst was packed into a stainless steel reactor and a gasmixture consisting of isobutylene (5%), oxygen (12%), steam (10%), andnitrogen (73%) was passed through the catalyst layer for a contactperiod of 2 seconds and reacted at 365° C.

The conversion of isobutylene was 95%, the selectivity for methacrolein87%, the selectivity for methacrylic acid 4.8%, and the single passyield for methacrolein and methacrylic acid combined was 87.2%.

EXAMPLE 2

Using the catalyst in Example 1 and t-butanol as the starting material,a reaction was carried out under the same conditions as in Example 1.This reaction gave a t-butanol conversion of 100%, a selectivity formethacrolein of 85.5%, a selectivity for methacrylic acid of 2.8%, and acombined single-pass yield for methacrolein and methacrylic acid of88.3%.

EXAMPLES 3-11

The following catalysts were prepared in the same manner as in Example1.

Example 3: Mo₁₂ W₀.3 Bi₀.8 Fe₂.5 Ni₃ Co₄ Sn₁ Pb₀.5 Sb₁.3 K₀.1 Cs₀.7

Example 4: Mo₁₂ W₀.5 Bi₀.8 Fe₃ Ni₅ Co₁ Mg₁ Zn₁ B₀.5 Sb₁.5 Cs₀.7

Example 5: Mo₁₂ W₀.5 Bi₁ Fe₂.7 Ni₇ Mn₀.5 Co₁ P₀.05 Sb₂ Rb₀.5 Zn₁

Example 6: Mo₁₂ W₀.5 Bi₁ Fe₃ Ni₇ Mn₁ Mg₂ Zn₀.5 S₀.2 Sb₁ Rb₀.2 Cs₀.3

Example 7: Mo₁₂ W₀.2 Bi₀.7 Fe₃ Ni₇ Mg₁ Pb₁ Si₀.8 Sb₁.5 K₀.3

Example 8: Mo₁₂ W₀.5 Bi₀.9 Fe₂.7 Ni₁ Co₅ Pb₁ Si₀.8 Se₀.8 Sb₁.5 Cs₀.7

Example 9: Mo₁₂ W₀.1 Bi₁ Fe₃ Ni₈ Zn₁ Sn₁ Ge₀.1 Sb₁ Rb₀.5 K₀.5

Example 10: Mo₁₂ W₀.5 Bi₁ Fe₃ Ni₆.5 Rb₀.7 Sb₂ Pb₂

Example 11: Mo₁₂ W₀.5 Bi₁ Fe₂.5 Ni₇ P₀.08 Zn₂ Pb₀.5 Sb₁.2 Cs₀.7

Using these catalysts, reactions were carried out under the samereaction conditions as in Example 1, save for the reaction temperature.The results are given in Table 1.

                  TABLE 1                                                         ______________________________________                                                   Conver-                  Single-pass                                          sion     Selectiv-                                                                              Selectiv-                                                                            yield of                                  Reac-      of iso-  ity for  ity for                                                                              (methacrolein                             tion       buty-    metha-   metha- +                                         Temp.      lene     crolein  crylic methacrylic                               (°C.)                                                                             (%)      (%)      acid (%)                                                                             acid) (%)                                 ______________________________________                                        Exam-  365     95.5     86     5.2    87.1                                    ple 3                                                                         Exam-  365     96       88     3.5    87.8                                    ple 4                                                                         Exam-  370     93       89     4.3    86.8                                    ple 5                                                                         Exam-  370     93       91     2.5    87.0                                    ple 6                                                                         Exam-  370     95       86     4.9    86.4                                    ple 7                                                                         Exam-  365     96       87     4      87.4                                    ple 8                                                                         Exam-  360     92       90     4.5    86.9                                    ple 9                                                                         Exam-  370     94.5     86     5      86.0                                    ple 10                                                                        Exam-  370     95       87     3.8    86.3                                    ple 11                                                                        ______________________________________                                    

EXAMPLES 12-20

These reactions were carried out on t-butanol as the starting materialusing the respective catalysts in Examples 3-11. All the other reactionconditions were the same as in the corresponding examples above. Theresults are given below in Table 2.

                  TABLE 2                                                         ______________________________________                                                                            Single-pass                                          Conver-  Selectiv-                                                                              Selectiv-                                                                            yield of                                  Reac-      sion     ity for  ity for                                                                              (methacrolein                             tion       of t-    metha-   metha- +                                         Temp.      butanol  crolein  crylic methacrylic                               (°C.)                                                                             (%)      (%)      acid (%)                                                                             acid) (%)                                 ______________________________________                                        Exam-  365     100      85     3.0    88.0                                    ple 12                                                                        Exam-  365     100      86     2.8    88.8                                    ple 13                                                                        Exam-  370     100      85.5   3.0    88.5                                    ple 14                                                                        Exam-  370     100      86     1.5    87.5                                    ple 15                                                                        Exam-  370     100      85     2.9    87.9                                    ple 16                                                                        Exam-  365     100      85     2.5    87.5                                    ple 17                                                                        Exam-  360     100      86     1.5    87.5                                    ple 18                                                                        Exam-  370     100      84     3.0    87.0                                    ple 19                                                                        Exam-  370     100      85     2.5    87.5                                    ple 20                                                                        ______________________________________                                    

COMPARATIVE EXAMPLE 1

A catalyst having the composition Mo₁₂ Bi₁ Fe₃ Ni₇ Mg₁.5 Zn₀.5 Sb₁.5Rb₀.8 was prepared in the same manner as in Example 1, but without usingthe 18.5 parts of ammonium paratungstate. A reaction was conducted usingthis catalyst under the same reaction conditions as in Example 1, givingan isobutylene conversion of 91%, a selectivity for methacrolein of 86%,a selectivity for methacrylic acid of 5.3%, and a single-pass yield formethacrolein and methacrylic acid combined of 83.1%.

The process was repeated in the same fashion using t-butanol, giving at-butanol conversion of 100%, a selectivity for methacrolein of 80%, aselectivity for methacrylic acid of 3.6%, and a single-pass yield formethacrolein and methacrylic acid combined of 83.6%.

COMPARATIVE EXAMPLE 2

A catalyst having the composition Mo₁₂ W₃ Bi₁ Fe₃ Ni₇ Sb₁.5 Rb₀.8 Mg₁.5Zn₀.5 was prepared in the same manner as in Example 1, except for theamount of ammonium paratungstate, which was increased to 184.8 parts. Areaction was conducted using this catalyst under the same reactionconditions as in Example 1, giving an isobutylene conversion of 70%, aselectivity for methacrolein of 75%, a selectivity for methacrylic acidof 5%, and a single-pass yield for methacrolein and methacrylic acidcombined of 56.0%. In addition, the same reaction as in Example 2 wascarried out, giving a t-butanol conversion of 100%, a selectivity formethacrolein of 58%, a selectivity for methacrylic acid of 2.8%, and asingle-pass yield for methacrolein and methacrylic acid combined of60.8%.

COMPARATIVE EXAMPLE 3

A catalyst having the composition Mo₁₂ W₀.3 Bi₁ Fe₃ Ni₇ Sb₁.5 Rb₀.8 wasprepared in the same manner as in Example 1, but without using the 90.8parts of magnesium nitrate and 35.1 parts of zinc nitrate. A reactionwas conducted using this catalyst under the same reaction conditions asin Example 1, giving an isobutylene conversion of 90%, a selectivity formethacrolein of 84%, a selectivity for methacrylic acid of 5%, and asingle-pass yield for methacrolein and methacrylic acid combined of80.1%. In addition, the same reaction as in Example 2 was carried out,giving a t-butanol conversion of 100%, a selectivity for methacrolein of76%, a selectivity for methacrylic acid of 5.2%, and a single-pass yieldfor methacrolein and methacrylic acid combined of 81.2%.

COMPARATIVE EXAMPLE 4

A catalyst having the composition Mo₁₂ W₀.3 Bi₄ Fe₃ Ni₇ Mg₁.5 Zn₀.5Sb₁.5 Rb₀.8 was prepared in the same manner as in Example 1, except forthe amount of bismuth nitrate, which was increased to 457.9 parts. Areaction was conducted using this catalyst under the same reactionconditions as in Example 1, giving an isobutylene conversion of 75%, aselectivity for methacrolein of 78%, a selectivity for methacrylic acidof 3%, and a single-pass yield for methacrolein and methacrylic acidcombined of 60.8%. In addition, the same reaction as in Example 2 wascarried out, giving a t-butanol conversion of 100%, a selectivity formethacrolein of 60%, a selectivity for methacrylic acid of 1.6%, and asingle-pass yield for methacrolein and methacrylic acid combined of61.6%.

COMPARATIVE EXAMPLE 5

A catalyst having the composition Mo₁₂ W₀.3 Bi₁ Fe₃ Ni₇ Mg₁.5 Zn₀.5Sb₁.5 Rb₂.5 was prepared in the same manner as in Example 1, except forthe amount of rubidium nitrate, which was increased to 87.0 parts. Areaction was conducted using this catalyst under the same reactionconditions as in Example 1, giving an isobutylene conversion of 70%, aselectivity for methacrolein of 80%, a selectivity for methacrylic acidof 4%, and a single-pass yield for methacrolein and methacrylic acidcombined of 58.8%. In addition, the same reaction as in Example 2 wascarried out, giving a t-butanol conversion of 100%, a selectivity formethacrolein of 58.5%, a selectivity for methacrylic acid of 2.3%, and asingle-pass yield for methacrolein and methacrylic acid combined of60.8%.

EXAMPLE 21

Reactions were conducted for 9000 hours under the same reactionconditions as in Example 1 using the catalysts in Examples 1 and 4. Theresults are given in Table 3.

                  TABLE 3                                                         ______________________________________                                                   Conver-                  Single-pass                                          sion     Selectiv-                                                                              Selectiv-                                                                            yield of                                  Reac-      of iso-  ity for  ity for                                                                              (methacrolein                             tion       buty-    metha-   metha- +                                         time       lene     crolein  crylic methacrylic                               (elapsed)  (%)      (%)      acid (%)                                                                             acid) (%)                                 ______________________________________                                        Exam-   5 hrs  95       87     4.8    87.2                                    ple 1 9000 hrs 94.5     86.8   4.8    86.6                                    cata-                                                                         lyst                                                                          Exam-   5 hrs  96       88     3.5    87.8                                    ple 4 9000 hrs 95       88     4.0    87.4                                    cata-                                                                         lyst                                                                          ______________________________________                                    

EXAMPLE 22

Reactions were conducted for 9000 hours under the same reactionconditions as in Example 2 using the catalysts in Examples 1 and 4. Theresults are given in Table 4.

                  TABLE 4                                                         ______________________________________                                                                            Single-pass                                          Conver-  Selectiv-                                                                              Selectiv-                                                                            yield of                                  Reac-      sion     ity for  ity for                                                                              (methacrolein                             tion       of t-    metha-   metha- +                                         time       butanol  crolein  crylic methacrylic                               (elapsed)  (%)      (%)      acid (%)                                                                             acid) (%)                                 ______________________________________                                        Exam-   5 hrs  100      85.5   2.8    88.3                                    ple 1 9000 hrs 100      85     2.5    87.5                                    cata-                                                                         lyst                                                                          Exam-   5 hrs  100      86     2.8    88.8                                    ple 4 9000 hrs 100      85.5   2.5    88.0                                    cata-                                                                         lyst                                                                          ______________________________________                                    

COMPARATIVE EXAMPLE 6

Table 5 gives the results obtained by running reactions for 9000 hoursunder the same reaction conditions as in Example 1 using the catalystsin Comparative Examples 1-5.

                  TABLE 5                                                         ______________________________________                                                    Conver-                  Single-pass                                          sion     Selectiv-                                                                              Selectiv-                                                                            yield of                                 Reac-       of iso-  ity for  ity for                                                                              (metha-                                  tion        buty-    metha-   metha- crolein +                                time        lene     crolein  crylic methacrylic                              (elapsed)   (%)      (%)      acid (%)                                                                             acid) (%)                                ______________________________________                                        Compar-                                                                                5 hrs  91       86     5.3    83.1                                   ative Ex-                                                                            9000 hrs 90       84     5      80.1                                   ample 1                                                                       catalyst                                                                      Compar-                                                                                5 hrs  70       75     5      56.0                                   ative Ex-                                                                            9000 hrs 60       75     5      48.0                                   ample 2                                                                       catalyst                                                                      Compar-                                                                                5 hrs  90       84     5      80.1                                   ative Ex-                                                                            9000 hrs 88       82     5      76.6                                   ample 3                                                                       catalyst                                                                      Compar-                                                                                5 hrs  75       78     3      60.8                                   ative Ex-                                                                            9000 hrs 70       77     4      56.7                                   ample 4                                                                       catalyst                                                                      Compar-                                                                                5 hrs  70       80     4      58.8                                   ative Ex-                                                                            9000 hrs 68       79     5      57.1                                   ample 5                                                                       catalyst                                                                      ______________________________________                                    

Table 6 gives the results obtained by conducting reactions for 9000hours under the same reaction conditions as in Example 2 using thecatalysts in Comparative Examples 1-5.

                  TABLE 6                                                         ______________________________________                                                                             Single-pass                                          Conver-  Selectiv-                                                                              Selectiv-                                                                            yield of                                 Reac-       sion     ity for  ity for                                                                              (metha-                                  tion        of t-    metha-   metha- crolein +                                time        butanol  crolein  crylic methacrylic                              (elapsed)   (%)      (%)      acid (%)                                                                             acid) (%)                                ______________________________________                                        Compar-                                                                                5 hrs  100      80     3.6    83.6                                   ative Ex-                                                                            9000 hrs 100      78.4   4.6    83.0                                   ample 1                                                                       catalyst                                                                      Compar-                                                                                5 hrs  100      58.4   2.4    60.8                                   ative Ex-                                                                            9000 hrs 100      54     2.3    56.3                                   ample 2                                                                       catalyst                                                                      Compar-                                                                                5 hrs  100      76     5.2    81.2                                   ative Ex-                                                                            9000 hrs 100      72.8   5.1    77.9                                   ample 3                                                                       catalyst                                                                      Compar-                                                                                5 hrs  100      60     1.6    61.6                                   ative Ex-                                                                            9000 hrs 100      56.2   1.5    57.7                                   ample 4                                                                       catalyst                                                                      Compar-                                                                                5 hrs  100      58.5   2.3    60.8                                   ative Ex-                                                                            9000 hrs 100      53.3   1.4    54.7                                   ample 5                                                                       catalyst                                                                      ______________________________________                                    

We claim:
 1. A process for the production of methacrolein andmethacrylic acid comprising the gas phase catalytic oxidation ofisobutylene or t-butanol using molecular oxygen in the presence of acatalyst having the composition

    Mo.sub.a W.sub.b Bi.sub.c Fe.sub.d Ni.sub.e Sb.sub.f X.sub.g Y.sub.h Z.sub.i A.sub.j O.sub.k

wherein Mo, W, Bi, Fe, Ni, Sb, and O are respectively molybdenum,tungsten, bismuth, iron, nickel, antimony, and oxygen; X is at least oneelement selected from the group consisting of potassium, rubidium, andcesium; Y is at least one element selected from the group consisting ofphosphorus, boron, sulfur, silicon, selenium, and germanium; Z is atleast one element selected from the group consisting of zinc and lead; Ais at least one element selected from the group consisting of magnesium,cobalt, manganese, and tin; and a, b, c, d, e, f, g, h, i, j, and krepresent the atomic ratios of the respective elements, and a=12,b=0.001-2, c=0.01-3, d=0.01-8, e=0.01-10, f=0.01-5, g=0.01-2, h=0-5,i=0.01-5, j=0-10, and k is the number of oxygen atoms sufficient tosatisfy the valences of the above components.
 2. A process according toclaim 1 wherein the catalyst employed contains zinc as the Z component.3. A process according to claim 1 wherein the catalyst employed containszinc as the Z component and cobalt as the A component.
 4. A processaccording to claim 1 wherein the catalyst employed contains phosphorusor boron as the Y component.
 5. A process according to claim 1, whereinb=0.01-2, c=0.1-2, d=0.1-5, e=0.1-10, f=0.1-3, g=0.1-2, h=0.001-2,i=0.1-5, and j=1-10.